Content impressions and interactions seem not to be registred

I’m using Piwik 3.0.1.

I’m trying to integrate content impressions and interactions tracking. I’ve set up the code on the front-end side, and trigger some content interactions, but they seem not to be reflected in the stats (Actions > Stats). I’ve even tried running

_paq.push(['trackContentInteraction', 'tabActivated', 'Content Name', 'Content Piece', '']);

Into the browser console when browsing the website, to no avail - the “Content” summary is still empty:

All the other stats (pageviews, visitors) seem to be working.

Am I missing something crucial?